Cu2ZnSnSe4 and Cu2ZnSn(S,Se)4 absorber films processed from co-evaporated Cu-Zn-Sn precursor films by post selenization and sequential sulfurization were investigated by varying Cu/(Zn + Sn) ratio and selenization/ sufurization temperatures. Structural, electrical and optical properties were largely dependent on the experimental parameters. The selenization process of the Cu-Zn-Sn precursors was successful in producing Cu2ZnSnSe4 phase with dense microstructure when the Cu/(Zn + Sn) ratio of 0.8 was initially used. The absorber led to a photovoltaic cell efficiency of ~1.04% with a short circuit current of ~21.9 mA/ cm2. Sequential sulfurization of the selenized films resulted in completely- transformed Cu2ZnSn(S,Se)4 phase with a minor secondary phase of Cu2S. Cell performance was not improved after sulfurization primarily due to poor microstructural features that became worse with increasing the Cu/(Zn + Sn) ratio.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant (No. 2011-0020285 ) funded by a Korean government. We acknowledge Dr. Bhaskar Mohanty for helpful discussion.
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry